Mattermost schemes teams endpoint exposes private team invite IDs

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Summary

CVECVE-2026-9820
StatePUBLISHED
AssignerMattermost
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-13 11:16:28 UTC
Updated2026-07-13 11:16:28 UTC
DescriptionMattermost versions 11.7.x <= 11.7.2, 10.11.x <= 10.11.19 fail to sanitize team objects returned by the scheme teams endpoint, which allows a user with the User Manager role to obtain invite links for private teams and use them to join or share access to those teams via the scheme teams API endpoint.. Mattermost Advisory ID: MMSA-2026-00671

Risk And Classification

Primary CVSS: v3.1 3.8 LOW from [email protected]

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N

Problem Types: CWE-862 | CWE-862 CWE-862: Missing Authorization

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary3.8LOWCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N
3.1CNACVSS3.8LOWCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
High
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mattermost Mattermost affected 11.7.0 11.7.2 semver Not specified
CNA Mattermost Mattermost affected 10.11.0 10.11.19 semver Not specified
CNA Mattermost Mattermost unaffected 11.8.0 Not specified
CNA Mattermost Mattermost unaffected 11.7.3 Not specified
CNA Mattermost Mattermost unaffected 10.11.20 Not specified

References

ReferenceSourceLinkTags
mattermost.com/security-updates [email protected] mattermost.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: 0x7oda7123 (en)

Additional Advisory Data

Solutions

CNA: Update Mattermost to versions 11.8.0, 11.7.3, 10.11.20 or higher.

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